Once the seeds have germinated, you can, and should, go back and thin out the excess. It's best to use scissors and just snip off the ones you're removing, as pulling them might disturb the root system of the ones you want to keep. Crowding plants too close together can have an adverse affect on their growth, health, and production.

You don't say what kind of seeds you are sowing: vegetables, herbs, flowers and whether they are annuals or perennials. Remember that while annuals have only one season to complete their mission (grow big and produce lots of seeds via flowers and fruit), perennials are in it for the long haul and will most likely take longer to reach full size and flowering.

Thanks for the reply. Sorry, I forgot to mention what I was growing lol. So far I have out Lupines, Black Eyed Susans and Salvia, all perennials. I try to stay away from annuals though Petunias smell awesome!